Delayed maturation and reduced crown width of the permanent first mandibular molar in all subgroups of cleft lip and palate.

OBJECTIVES: Surgical closure of the cleft damages nerves and blood supply in the area and may possibly negatively influence dental development in children with cleft lip and palate (CLP). Previous studies of the permanent first mandibular molar (M1inf ) in children with unilateral complete CLP found delayed maturation and decreased follicle/crown width before any surgical interventions. This study aimed to investigate if these findings are representative for the total population of individuals born with CLP. SETTING AND SAMPLE POPULATION: A population-based consecutive longitudinal sample of 224 children with clefts: 183 with CLP (66 with complete [47 unilateral, 19 bilateral], 117 with incomplete [70 unilateral, 47 bilateral], and 41 with unilateral incomplete cleft lip (controls), was examined pre- and post-lip closure (at 2 and 22 months of age). MATERIAL AND METHODS: In lateral cephalometric X-rays (obtained as part of a standard treatment protocol), M1inf follicle maturation and follicle/crown width were assessed. Mantel-Haenszel test and Pearson's correlation coefficient R were used to describe relationships. Differences between group means were tested using Wilcoxon rank sum test. Significance level was set to 5%. RESULTS: Follicle maturation was significantly delayed in all groups with CLP compared to that in controls (P < .01). Follicle and crown width were significantly reduced in all CLP groups compared with those in controls (P < .01). Sex did not influence these variables. CONCLUSION: Delayed follicle maturation and decreased follicle/crown/tooth size were found to be part of the congenital traits characterizing individuals with all types of CLP and not a result of surgical iatrogenesis.